As disclosed in the above-referenced application, metal standing rib roofs consist of multiple side-by-side panels of channel cross section. The standing webs of the roof panels are intervened by attaching clips whose feet are anchored to underlying purlins. A stand-off space suitable for receiving thermal insulation can be provided between the bottoms of the roof panels and the tops of the purlins. Cap strips are closed around top lateral flanges of the roof panels and superposed flanges of the attaching clips to complete the formation of standing T-ribs and to permanently join the roof panels in weather-tight relationship.
In the prior art, when it is desired to provide a skylight in roofs of this type, it has been customary to provide a translucent channel member formed of plastic or fiberglass and being of substantially the same width as the metal roof channels. Skylight suspension members in the form of metal angles are riveted to the side standing webs of the skylight panel and these angle members are then engaged with the panel attaching clips and cap strips in the usual manner to incorporate the skylight panel in the metal roof structure.
This customary construction presents serious problems which have not heretofore been solved in the prior art.
The differential in expansion and contraction between the metal roof panels and non-metal skylight panel is so great that the resulting pressures on the rivets can cause them to enlarge or distort the rivet holes and, in some cases, the riveted connections have actually torn or ruptured. This of course results in loss of roof integrity and strength and roof leakage.
In the prior art arrangements, the heavy stresses caused by normal roof expansion and contraction are applied directly to the skylight panel or panels which are incapable of withstanding the stresses, resulting in weakening the entire roof system. A metal roof must be able to expand and contract both laterally and longitudinally of the roof panels and as a result of this tremendous stresses are created and the materials employed must be able to withstand the stresses without failure or permanent deformation. The dissimilar materials involved providing a skylight renders it impossible for the structure to withstand the stresses without damage.
Another problem encountered in the prior art is that the non-metallic skylight panels readily abrade and wear due to frictional contact with underlying purlins or other metal parts of the roof system. As the roof expands and contracts, the purlins are subjected to limited rotation and such movements, even though small, can readily abrade and damage the translucent skylight panel formed of plastic or fiberglass.
The invention has as its objective to completely solve the above problems of the prior art by providing a skylight panel or panels for a standing rib metal roof whose use will not significantly lessen the structural integrity of the roof or create any tendency for the roof to leak as a result of having the skylight therein.
In accordance with the invention, all riveting of the skylight panel is eliminated and opposite sides of the skylight panel are supported by continuous metal channels or holders which interfit with the roof attaching clips and closable cap strips while suspending the non-metallic skylight panel in such a way that it is weather-tight and substantially relieved of heavy stresses due to roof expansion and contraction and is also supported out of contact with the purlins or other metallic parts of the roof system to thus avoid abrading the skylight panel. By means of the invention, it is necessary to form any holes whatsoever in the skylight panel and thus its inherent strength is unimpaired.